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Subject[PATCH v3] exfat: Avoid allocating upcase table using kcalloc()
Date
The table for Unicode upcase conversion requires an order-5 allocation,
which may fail on a highly-fragmented system:

pool-udisksd: page allocation failure: order:5, mode:0x40dc0(GFP_KERNEL|__GFP_COMP|__GFP_ZERO), nodemask=(null),cpuset=/,mems_allowed=0
CPU: 4 PID: 3756880 Comm: pool-udisksd Tainted: G U 5.8.10-200.fc32.x86_64 #1
Hardware name: Dell Inc. XPS 13 9360/0PVG6D, BIOS 2.13.0 11/14/2019
Call Trace:
dump_stack+0x6b/0x88
warn_alloc.cold+0x75/0xd9
? _cond_resched+0x16/0x40
? __alloc_pages_direct_compact+0x144/0x150
__alloc_pages_slowpath.constprop.0+0xcfa/0xd30
? __schedule+0x28a/0x840
? __wait_on_bit_lock+0x92/0xa0
__alloc_pages_nodemask+0x2df/0x320
kmalloc_order+0x1b/0x80
kmalloc_order_trace+0x1d/0xa0
exfat_create_upcase_table+0x115/0x390 [exfat]
exfat_fill_super+0x3ef/0x7f0 [exfat]
? sget_fc+0x1d0/0x240
? exfat_init_fs_context+0x120/0x120 [exfat]
get_tree_bdev+0x15c/0x250
vfs_get_tree+0x25/0xb0
do_mount+0x7c3/0xaf0
? copy_mount_options+0xab/0x180
__x64_sys_mount+0x8e/0xd0
do_syscall_64+0x4d/0x90
entry_SYSCALL_64_after_hwframe+0x44/0xa9

Convert kcalloc/kfree to their kv* variants to eliminate the issue.

Cc: stable@vger.kernel.org # v5.7+
Signed-off-by: Artem Labazov <123321artyom@gmail.com>
---
v2: replace vmalloc with vzalloc to avoid uninitialized memory access
v3: use kv* functions to attempt kmalloc first

fs/exfat/nls.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/exfat/nls.c b/fs/exfat/nls.c
index 675d0e7058c5..314d5407a1be 100644
--- a/fs/exfat/nls.c
+++ b/fs/exfat/nls.c
@@ -659,7 +659,7 @@ static int exfat_load_upcase_table(struct super_block *sb,
unsigned char skip = false;
unsigned short *upcase_table;

- upcase_table = kcalloc(UTBL_COUNT, sizeof(unsigned short), GFP_KERNEL);
+ upcase_table = kvcalloc(UTBL_COUNT, sizeof(unsigned short), GFP_KERNEL);
if (!upcase_table)
return -ENOMEM;

@@ -715,7 +715,7 @@ static int exfat_load_default_upcase_table(struct super_block *sb)
unsigned short uni = 0, *upcase_table;
unsigned int index = 0;

- upcase_table = kcalloc(UTBL_COUNT, sizeof(unsigned short), GFP_KERNEL);
+ upcase_table = kvcalloc(UTBL_COUNT, sizeof(unsigned short), GFP_KERNEL);
if (!upcase_table)
return -ENOMEM;

@@ -803,5 +803,5 @@ int exfat_create_upcase_table(struct super_block *sb)

void exfat_free_upcase_table(struct exfat_sb_info *sbi)
{
- kfree(sbi->vol_utbl);
+ kvfree(sbi->vol_utbl);
}
--
2.26.2
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